Defending champion Serena Williams won her much-anticipated US Open showdown with Sloane Stephens while Li Na avenged a painful loss in Rome to join the world number one in the last eight.
Williams defeated US 15th seed Sloane Stephens 6-4, 6-1 to reach the US Open quarter-finals, winning eight of the last nine game in avenging a loss that ousted her from the 2013 Australian Open.
"It definitely felt like a bigger match because Sloane is such a great player, but I had to stay focused in the moment," Williams said. "I just tried the whole time to do what I wanted to, stay calm and stay relaxed."
Williams booked a quarter-final against Spanish 18th seed Carla Suarez Navarro, who upset German eighth seed Angelique Kerber 4-6, 6-3, 7-6 (7/3).
Also booking a quarter-final matchup were Chinese fifth seed Li, who beat Serbian ninth seed Jelena Jankovic 6-3, 6-0, and Russian 24th seed Ekaterina Makarova, who upset Polish third seed Agnieszka Radwanska 6-4, 6-4.
Li, the 2011 French Open champion, matched her best US Open result by reaching the last eight.
"Maybe today was the best match of my whole life," Li said, adding her strategy against Makarova would be to "Play aggressive. I wish I can play the same level like today."
Li improved to 5-4 against Jankovic, motivated by the sting of a loss in their most recent match in a round-of-16 affair last May in Rome.
"Last time I lost to her in Rome I was feeling so sad. I was feeling I played so good. I said, 'You have to remember how you felt after Rome and not have that feeling any more.'"
Suarez Navarro hit 45 winners and took advantage of 50 unforced errors by Kerber to rally for the victory after two hours and 41 minutes. Radwanska dropped the last eight games and was ousted in the fourth round at the US Open for the fourth time, having never reached the quarter-finals.
"I want to know as well what happened," Radwanska said. "She was a little nervous in the beginning and she started playing better and better and I didn't do anything to win that first set.
